Currently, my app with x.x.x format, but now by the next release we want to make it version format to x.x.x.x. Now created a version in itunesconnect with x.x.x.x, but the problem is while uploading build to apple its giving an error that "The value for key CFBundleShortVersionString 'x.x.x.x' in the info.plist file must be a period-separated list of at most three non- negative integers."
I have seen many apps with 'x.x.x.x' format in appstore. but why they are not allowing? have they(apple) changed any thing recently?
x.x.x is the largest period-separated format allowed. You cannot use x.x.x.x (when building with Xcode 6. Older Xcode versions allowed x.x.x.x version format).
Probably the input field in iTunes Connect does not validate the input you provide for this case, so you were able to enter it there. The issue is that Xcode does not allow you to use it, and since your version string is validated when you upload the binary, you should use the format x.x.x.